Use of the mono- and di-carbalkoxy-diarylthioureas as accelerators in the vulcanization of rubber



Patented Nov. 25, 1930 i NUNITE'D STATES PATENT "OFFICE" snort. JOHN TURRELL onoNsrrAw AND wILLraM JOHNSON sMITn NAUNTON, or

BLACKLEY, MANCHESTER, ENGLAND, AssIGNons T BRITISH DYESTUFFS CORPORA- rIoN LIMITED, or MANCHESTER, E LAND I USE or :unn MoNo AND DI-GARBALKQXY-DIARYLTHIOUREAS AS ACCELERATORS I THE VULGANIZATION 03E RUBBER Q No Drawing. Application filed October 27, 1926, Serial No. 144,643, and in Great I Britain March 1, 1926.

We have discovered that the symmetrical thioureas hav ng the structure,

NH.Ar.COOR o s I NH.A1.COOR

in which It represents an alkyl group and Ar represents adivalent aromatic residue, and 111; which the carbalkoxy group in each nucleus is ortho to the NH group, are Valuable suitable accelerators accelerators of the vulcanization of rubber. In View of the acidic nature of the carboXy groups in these bodies, it was contrary to eX- pectation that they should be very much more active than other classes of substituted ureas. For example, a simple rubber (caoutchouc) mix containing 100 parts smoked sheet, 10 parts zinc oxide and 10 parts of sulphur and 1.63 parts ofdi-ortho-carbethoxydiphenylthioure a, having the structure ONES s .NH

peratures. According to some modern views, it Is not the accelerator as applied Which is eflectivei, but the accelerator as changed or decomposed by the heat used in vulcanlzation which is responsible for the effects produced. It will accordingly be understood that, in referring to the di o-carbalkoxyaryl thioureas themselves as accelerators, We mean to include also the products formed when these aresubjected to a moderately high temperature.

What we claim and desire to secure by Letcanizing agents and an ortho carbalkoxyaryl thiourea having the formula COOCzHs COOCzHb and subjecting the mixture to vulcanizing in- 2. A vulcanized composition containing reaction products of rubber, vulcanizing agents and an ortho carbalkoxyaryl thiourea having the formula.

In witness whereof, we aifiX our signatures.

CECIL JOHN TURRELL CRONSHAW. WILLIAM JOHNSON SMITH NAUNTON.

by the method described by Dyson and George in the Journal of the London Chemical Society, 1924, vol. 125, p. 1708, i. e. by the action of thiophosgene upon alkyl anthranilates. The crude reaction mixture ma be used, but, we prefer to employ the pro ucts isolated as described by Dyson and George, in order toobtain theactive principle (the stated thioureas). During vulcanization e accelerator, with the other contents of the mix, exposed to moderately high tom 

